Various medical procedures require fluids to be delivered to specific locations within the body, typically via a fluid delivery catheter. A narrow steerable guidewire is often used to maneuver through narrow, tortuous, and/or branching body passageways. After the guidewire has been directed to the desired location, a fluid delivery catheter may be inserted over the guidewire. The guidewire is usually removed before fluid delivery begins. Guidewires which are themselves capable of fluid delivery (such as that disclosed in U.S. Pat. No. 5,322,508) are also known in the art.
In current angiographic procedures, a relatively large (5 French (1.65 mm) or larger) catheter is used to inject a contrast material into vascular spaces, such as the coronary arteries and cerebral vessels. Contrast material is a radiopaque liquid typically including iodine or an equivalent component, and having a viscosity 2-10 times that of water. During or after injection of the radiopaque contrast material, an x-ray or fluoroscopic image is taken of the injection site.
Large angiographic catheters are typically required to perform such procedures because of the relatively high viscosity of commonly used contrast materials, and because of the relatively large amount of contrast material required to produce a good quality angiographic image. But even when relatively large catheters are used, the contrast material must be delivered under high pressure to ensure that a sufficient quantity of contrast material is delivered.
When contrast material is injected at a rate necessary to perform coronary angiography selectively into either the right or left coronary artery, the relatively high velocity associated with the injection frequently results in recoil of the catheter, so that the contrast material may be injected into the aorta rather than selectively into the coronary artery. The relatively high velocity of contrast material injection also increases the potential for inducing mechanical trauma to the inner surface of a blood vessel. Accordingly, angiographic catheters smaller than about 5 French are not ordinarily suitable for use in such procedures because of the even higher velocities required to inject a sufficient quantity of contrast material.
The use of conventional angiographic catheters presents other problems as well. For example, a guidewire is usually needed to advance the catheter from the peripheral arterial access site to a location of interest. This guidewire is then removed from the lumen of the catheter to allow the injection of contrast material through the same lumen. The use of both a wire and a catheter requires time for preparation and removal, and the overall cost of the equipment is increased by the need for two devices for each procedure. Moreover, in coronary angiographic procedures, the right and left coronary arteries usually require catheter tips having different shapes to facilitate engagement of the ostium of the coronary artery with the distal tip of the catheter.
Accordingly, there remains a need in the art for an inexpensive, low profile, easy to use catheter or fluid delivery device that can deliver large amounts of contrast material without causing trauma to vascular walls, and without causing recoil of the catheter itself.
In angioscopy procedures, a fiberoptic angioscope positioned with a guide catheter is used to image the interior of a blood vessel. To produce a clear image, the blood within the vessel is displaced, usually with a transparent saline solution. Current angioscopy products, such as the ImageCath.RTM. coronary angioscope by Guidant Corporation, include an angioscope within an outer catheter that provides a balloon to stop antegrade blood flow, and saline to displace blood within a vessel.
While the Guidant device works for its intended purpose, the relatively large profile of the outer catheter (4.5 French, or approximately 1.5 mm) requires the use of a very large (8 French, or approximately 2.6 mm) guide catheter to deliver the Guidant device to the desired location. The requirement for such a large guide catheter makes the Guidant angioscope difficult or impossible to use in certain locations, such as narrow or tortuous vessels. Accordingly, there remains a need in the art for a low profile angioscopy device that can be used to image areas accessible through narrow or tortuous blood vessels.
During balloon angioplasty procedures, a catheter equipped with a small balloon is inserted (usually over a guidewire) into an artery that has been narrowed, typically by the accumulation of fatty deposits. The balloon is then inflated to clear the blockage or lesion and widen the artery. Upon balloon inflation, blood flow distal to (that is, "downstream" from) the inflated balloon may be almost completely stopped.
Myocardial ischemia (that is, a reduction in blood perfusion to the heart muscle) occurs transiently in the majority of patients undergoing coronary angioplasty procedures, such as balloon angioplasty, directional atherectomy, rotational atherectomy, and stent deployment. The permissible duration of occlusion due to balloon inflation or other device deployment is normally determined by the severity of myocardial ischemia. Typically, evidence of severe ischemia (including patient chest pain and ECG changes) requires that the operator deflate the balloon or remove the occlusive device after approximately 60 to 120 seconds. For anatomically difficult lesions, such as type B and C lesions, longer periods of balloon inflation (or other device deployment) are frequently desirable for the first balloon inflation or other device deployment.
Autoperfusion balloon catheters, and catheters of the type disclosed in U.S. Pat. No. 5,322,508, can in some circumstances allow longer periods of balloon inflation. However, the blood (or other physiologic liquid) flow through such devices is frequently insufficient to provide an adequate oxygen supply to tissues distal to the angioplasty balloon or other occlusive device.
Recent advances in the generation and application of oxygen supersaturated solutions have made it possible to deliver greater amounts of oxygen to tissues distal to an angioplasty balloon. U.S. Pat. No. 5,407,426, and pending U.S. applications Ser. No. 08/273,652, filed Jul. 12, 1994, entitled "Method for Delivering a Gas-Supersaturated Fluid to a Gas-Depleted Site and Use Thereof"; U.S. Ser. No. 08/353,137, filed Dec. 9, 1994, entitled "Apparatus and Method of Delivery of Gas-Supersaturated Liquids"; U.S. Ser. No. 08/453,660, filed May 30, 1995, entitled "Method for Delivering a Gas-Supersaturated fluid to a Gas-Depleted Site and Use Thereof"; U.S. Ser. No. 08/465,425, filed Jun. 5, 1995, entitled "Method for Delivery of Gas-Supersaturated Liquids"; U.S. Ser. No. 08/484,279, filed Jun. 7, 1995, entitled "Apparatus and Method of Delivery of Oxygen-Supersaturated Physiologic Solutions During Clinical Procedures"; and U.S. Ser. No. 08/484,284, filed Jun. 7, 1995, entitled "High Pressure Gas Exchanger", which are incorporated herein by reference, disclose various methods for the generation and application of oxygen supersaturated liquids.
As is described in the above referenced patent applications, the generation, transport and delivery of oxygen supersaturated liquid may require the application of very high hydrostatic pressures. Accordingly, there remains a need for a high pressure fluid delivery device capable of infusing bubble-free fluid, which is supersaturated with oxygen, to vessels or ducts through and beyond the central lumen of a balloon angioplasty catheter or similarly occlusive device.